body{
    margin:0;
    padding:0;
}
ul{
    list-style: none;
    margin: 0;
    padding: 0;
}
nav{
    height: 60px;
    background-color: rgb(51, 51, 51);
}
/* 一级菜单 */
.menu-box>li{
    float: left;
    
     
}
.menu-box li{
    position: relative;
}
.menu-box>li a{
    height: 60px;
    width: 100px;
    color: rgb(189, 188, 188);
    background-color: rgb(51, 51, 51);
    text-decoration: none;
    display: block;
    text-align: center;
    line-height: 60px;
    border-left:1px solid transparent;

}

.menu-box li:hover>a{
    border-color: tomato;
    color: rgb(234, 235, 233);
    background-color: rgb(216, 124, 96);
}
/* 二级菜单 */
.submenu{
    display: none;
    position: absolute;
    left:0;
    top:60px;
}
.menu-box>li:hover .submenu {
    display: block;
}
